Process of filling a discharge chamber with mercury and product



March 29, 1960 c. CAPPELLETTI ET 2,930,921

, PROCESS OF FILLING A DISCHARGE CHAMBER v WITH MERCURY AND PRODUCT Filed May 9. 1955 INVENI'ORS Cahla C 5'5 am {WWW I ATTORNEY 5 United States Patent PROCESS OF FILLING A DISCHARGE CHAMBER WITH MERCURY AND PRGDUCT Carlo Cappelletti, Baden, Gysbert Jacob -Ekkers,Wet-

fingen, and Walter Meier, Baden, Switzerland, assignors to Patelhold Patentverwertungs- & Elektro-Holding A.-G., Glarus, Switzerland Application May 9, 1955, Serial No. 507,183

Claims priority, application Switzerland May 28, 1954 4 Claims. or. 313-174 The following methods for filling a discharge chamber with mercury are known.

(a) The' insertion of the mercury into the chamber before the evacuation there0f.T his method has the disadvantage that thevessel cannot be heated to a temperature sufl'lcient for a thorough degassing because the mercury would be vaporized and the mercury vapor would be lost through the pump. Besides, the mercury readily may become contaminated.

(b) Introduction of mercury into the chamber cannected to the pump after the evacuation.In this method the mercury cannot be accurately measured and the process is expensive and requires special pumping equipment.

(c) The liberation of the mercury in the chamber,

after it has been evacuated, by decomposition of mercury oxide which is present on a heatable support within the chamber.-The disadvantage of this method is that there is a large amount of oxygen which cannot be removed from the chamber quickly enough with the usual pumping equipment. The long pumping time required increases the danger of damage by oxidation. r

The process according to the present invention involves a further development of process ,(c) described above. It avoids the mentioned disadvantage of method (0) by immediately chemically binding the oxygen liberated by the decomposition of the mercury oxide. In ac- The iron present'in the mixture serves to moderate the otherwise explosive reaction. A suitable'ratio of the ingredients of the mixture is 1 part by weight of the mercury oxide, 1 part by weight of zirconium and 2 parts by weight of iron.

In place of zirconium any other reducing agent may be used which is not vaporized at the reaction temperature. 'Zirconium is especially adapted for economical use. In place of iron other metals may be used such as nickel, manganese, chromium or cobalt.

An embodiment of the invention is illustrated in the accompanying drawing.

For carrying out the process a support is provided within the chamber and a compressed pill formed of the above mentioned materials in powdered form is secured to the support. The chamber is then evacuated in the known manner at a temperature of, for example, 400 C. After the evacuated chamber has cooled the carrier alone is heated to about 700 C. to start the reaction. This may be done advantageously by magnetic induction which of course requires that the carrier must be made of metal. The carrier advantageously can be made of nickel which is easy to degas. The mercury which is liberated and vaporized by the reaction condenses on the cold parts of the chamber. The amount of mercury which is lost through the pump is not worth mentioning. There is no other gaseous or volatile material which remains to be pumped out or which will contaminate the chamber. The reaction residue forms a coherent, hard sinter of ZrO Zr, Fe O and Fe. Consequently the chamber can be sealed shortly after the burning of the pill.

The purity of the mercury generated and released by the mixture depends upon the use of pure mercury oxide. An especial advantage of the simple and inexpensive process is the accurate dosability'of the mercury oxide.

A discharge chamber made in accordance with the invention is generally characterized in that it containsthe carrier or support upon which a sinter body has been formed, said sinter body containing the oxide of the reducing agent, unconsumed reducing agent and oxide of the metal used to moderate the reaction.

Referring to the drawing 1 is the discharge chamber referred to above, 2 is the electrode, 3 is the electrode -support,'4 is the support for the mixture of mercury oxide, reducing agent and reaction retarder and 5 is a compressed pill of said mixture.

We claim:

1. Process for filling a discharge chamber with me cury which comprises supporting therein a mixture of mercury oxide, a first metallic reducing agent capable of thermite type reaction with the mercury oxide to liberate mercury and form a stable, non-volatile oxide thereof, said reducing agent being not volatile at the reaction 7 temperature, and a second metallic reducing agent capable of moderating said thermite type reaction, evacuating the chamber and heating said mixture to a temperature suflicient to initiate said thermite reaction.

2. A process of filling a discharge chamber with mercury which comprises supporting therein a mixture of v. mercury oxide, zirconium and iron, evacuating the cham- References Cited in the file of this patent UNITED STATES PATENTS 1,780,504 Risler Nov. 4, 1930 1,855,901 Bareiss et a1. Apr. 26, 1932 1,878,159 Mailey Sept. 20, 1932 Kuhne et a1. July 23, 1940 

